Recently, High Definition Multimedia Interface (HDMI)™ has become popular as a communication interface which transmits an uncompressed (baseband) image signal (image data) and a digital audio signal (audio data) accompanying with the image signal at a high speed. An HDMI source device on a data transmission side is connected to an HDMI sink device on a data reception side through the HDMI interface. For example, there may be an AV system in which a Blu-ray disc (BD) recorder, a set top box (STB), and another audio visual (AV) source as the HDMI source device and a television receiver, a projector, and another display as the HDMI sink device are connected to each other through the HDMI interface.
A system configuration in which an HDMI repeater provided with an HDMI input and an HDMI output is interposed between the HDMI source device and the HDMI sink device is also known (for example, refer to Patent Documents 1 and 2).
The HDMI repeater device may perform processing of superimposing graphics such as a menu operated by a user on the uncompressed image data which is input by HDMI in addition to characteristic correction of a transmission signal such as wavelength equalization. At that time, it is considered to be general that the HDMI repeater controls a dynamic range of a graphics generating unit on the premise of viewing with a monitor of standard luminance (100 cd/m2).
The uncompressed image data output from the HDMI source device might be transmitted after an original image having a standard or higher luminance dynamic range is subjected to dynamic range conversion to be compressed to have the standard luminance dynamic range.
Also, recently, with development in display technology, a display device such as an organic electro-luminescence display and a liquid crystal display (LCD) which may display an image brighter than the standard luminance of approximately 1000 cd/m2, for example, is commercially available. When the HDMI sink device is the display device having such a wide dynamic range, the image display to make use of its capability becomes possible by performing dynamic range reverse conversion on the image data on which the dynamic range conversion is performed on the HDMI source device side to return the same to the image data having original high luminance dynamic range.
However, when an graphics image having the standard luminance dynamic range is superimposed by the HDMI repeater interposed between the HDMI source device and the HDMI sink device, there might be a case in which the dynamic range of the graphics image displayed on the monitor excesses that supposed when the dynamic range reverse conversion is performed on the HDMI sink device.